1. Field of the Invention
The present invention relates to a wafer drying apparatus. More particularly, the present invention relates to a wafer drying apparatus in which a heater is provided at an injection nozzle that ejects isopropyl alcohol to a dry room, thereby activating the isopropyl alcohol in order to quickly dry pure water on a wafer.
2. Description of the Related Art
Generally, semiconductor devices are fabricated from wafers by utilizing various types of semiconductor fabricating apparatuses. During formation of semiconductor devices, impurities such as polymer, dust, various types of powders, etc. may remain on a wafer while the wafer is processed. Such impurities remaining on a wafer cause a decrease in semiconductor device manufacture yield. Consequently, a washing process for washing and drying the wafer is necessarily performed in order to remove the impurities.
At this time, pure de ionized water (DIW) is generally used for washing a wafer. Since pure water has a tendency to dissolve a wafer made of a silicon material, water spots are formed on the wafer shortly after washing in pure water. In order to prevent the formation of such water spots, wafers must be dried quickly after being washed in pure water.
The principal methods for drying wafers are a vapor dry method and a Marangoni dry method. The Marangoni method is based on a Marangoni principle wherein surface tension of a liquid phase material is used to dry a wafer. The Marangoni dry method has been widely used in various types of applications.
FIG. 1 illustrates a schematic diagram of a conventional wafer drying apparatus in which the Marangoni principle is applied. Referring to FIG. 1, the wafer drying apparatus comprises a washing tank 10, a hood 20, a storing tank 30, and a nitrogen supplier 40. The hood 20 supplies isopropyl alcohol (IPA) for drying a wafer (W) washed in the washing tank 10 wherein pure water is stored. The storing tank 30 is charged with a chemical (IPA) for drying a wafer. The nitrogen supplier 40 stores a carrier gas, i.e., nitrogen gas, for transferring the IPA from the storing tank 30 to an injection nozzle 21 of the hood 20. The hood 20 has a plurality of distributing pipes 22 formed at a bottom surface thereof for diffusing IPA on the wafer.
Operation of the apparatus as constructed will now be described with reference to FIGS. 1 and 2. The wafer (W) is first washed in the washing tank 10. The washed wafer is lifted to a dry room 11 by a lifter 12 to be dried therein. When the wafer (W) is transferred to the dry room 11 and secured therein, IPA vapors are created by a bubble maker 31 contained in the storing tank 30.
The IPA vapor is transferred to the hood 20 via first, second, and third pipes P1, P2, and P3, respectively, by the carrier gas from the storing tank 40 and ejected to the dry room 11 through the injection nozzle 21. At this time, the ejected IPA vapor is uniformly distributed in the dry room 11 and the wafer (W) in the dry room 11 is dried by the Marangoni principle.
However, there is a problem with this conventional method in that the IPA supplied to the wafer is at room temperature and therefore cannot dry the wafer quickly enough to prevent formation of water spots on the wafer. Particularly, such a wafer drying method is not able to properly cope with a situation in which a wafer is going to be diametrically enlarged because more water spots are formed on the wafer as the wafer is enlarged.
To solve a problem as described above, it is a feature of an embodiment of the present invention to provide a more efficient wafer drying apparatus in which isopropyl alcohol (IPA) supplied to a hood is activated by heating, thereby increasing its diffusion efficiency in the hood and allowing it to quickly vaporize pure water on a wafer.
It is another feature of an embodiment of the present invention to provide a more efficient wafer drying apparatus that is capable of coping with a situation in which a diameter of a wafer is enlarged and the wafer is highly integrated, while maintaining an improved drying efficiency.
In order to achieve the above features of the present invention, a wafer drying apparatus is provided, including: a washing tank for storing pure water; a hood positioned at an upper portion of the washing tank; an injection nozzle for ejecting IPA positioned in the hood; a storage tank for storing the IPA; a bubble maker in the storage tank to create IPA vapor; a nitrogen supplier for storing a carrier gas for transferring the IPA vapor in the storage tank to the hood; and a heater provided near the injection nozzle to heat the IPA vapor that is ejected through the injection nozzle to a predetermined temperature, thereby uniformly diffusing the IPA vapor.